JP2012042250A - Vibration type angular velocity sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a vibration type angular velocity sensor that is compact, and has high sensitivity and quick response.SOLUTION: The vibration type angular velocity sensor includes a support part, a weight part, a plurality of beam parts extended from the weight part to the support part and supporting the weight part respectively, excitation means of exciting the weight part in a plurality of directions by time-division driving, detection means of detecting motion of the weight part relative to the support part, spring constant stabilization means formed nearby a boundary with the beam parts of at least one of the support part and weight part, and elastically deforming in an extension direction of the beam parts according to tension of the beam parts, but substantially not deforming in a main deformation direction of the beam parts, and a damper coupled to the spring constant stabilization means and damping vibration of the spring constant stabilization means.

Description

  The present invention relates to a vibration type angular velocity sensor, and more particularly to a vibration type angular velocity sensor configured as MEMS (Micro Electro Mechanical Systems).

  Conventionally, a vibration type angular velocity sensor configured as a MEMS is known. In the vibration type angular velocity sensor, the sensitivity increases as the amplitude of the reference vibration increases. Therefore, the weight portion is excited at a frequency near the natural frequency determined by the shape of the weight portion and the shape of the elastic body supporting the weight portion. However, when the elastic body supporting the weight portion extends, the spring constant of the elastic body changes, and the natural frequency changes accordingly. Such a change in natural frequency is called a hard spring effect. For a certain amplitude, the hard spring effect tends to occur as the elastic body becomes smaller. Since it is difficult to excite following the change of the natural frequency due to the hard spring effect, it becomes difficult to realize a reference vibration having a large amplitude as the vibration type angular velocity sensor is downsized. As described in Patent Documents 1, 2, and 3, the beam portion as the elastic body that supports the weight portion has a bent portion, for example, the beam portion as the elastic body that supports the weight portion, such as a T-shape. And the natural frequency change due to the hard spring effect is less likely to occur.

JP 2000-199714 A JP 2007-333665 A International Publication WO00-079288 Pamphlet JP 2002-55117 A

However, if the beam portion itself is softened by forming a bent portion or the like, the spring constant and the natural frequency are greatly reduced. Therefore, the conventional method cannot reduce the hard spring effect of the elastic body while maintaining the target natural frequency. That is, the vibration type angular velocity sensor has a problem that, as the size of the vibration type angular velocity sensor is reduced, it is difficult to realize a reference vibration having a large amplitude and it is difficult to increase sensitivity.
In addition, in a vibration type angular velocity sensor that detects three components whose angular velocities are orthogonal by vibrating the weight portion in two directions by time-division driving, the vibration direction cannot be switched until the vibration in one direction is sufficiently attenuated. There is a problem that responsiveness deteriorates.

  The present invention has been created to solve this problem, and an object thereof is to provide a vibration type angular velocity sensor that is small in size and has high sensitivity and responsiveness.

  (1) A vibration type angular velocity sensor for achieving the above object includes a support portion, a weight portion, a plurality of beam portions extending from the weight portion to the support portion and supporting the weight portion, Near the boundary between excitation means for exciting the weight part in a plurality of directions by time-division driving, detection means for detecting movement of the weight part with respect to the support part, and the beam part of at least one of the support part and the weight part A spring constant stabilizing means that is elastically deformed in the extending direction of the beam part according to the tension of the beam part and does not substantially deform in the main bending direction of the beam part, and the spring constant stabilizing means, And a damper for coupling and damping the vibration of the spring constant stabilizing means.

  According to the present invention, the spring constant stabilizing means elastically deforms in the extending direction of the beam portion according to the tension of the beam portion, thereby suppressing the extension of the beam portion. For this reason, according to the present invention, even if the amplitude of the reference vibration of the weight portion is increased, a change in the natural frequency due to the hard spring effect can be suppressed. That is, according to the present invention, a vibration type angular velocity sensor with high sensitivity can be realized. Further, the spring constant in the extending direction of the beam portion is significantly larger than the spring constant in the main deflection direction of the beam portion. Therefore, even if the spring constant of the spring constant stabilizing means in the extending direction of the beam portion is considerably large, the hard spring effect of the beam portion can be suppressed. By setting the spring constant of the spring constant stabilizing means in the extending direction of the beam part sufficiently large, it is possible to prevent the natural frequency of the weight part from being significantly lowered by the spring constant stabilizing means. Further, since the vibration of the spring constant stabilizing means is attenuated by the damper, the time required for switching the vibration direction of the weight portion in the time-division driving can be shortened and the responsiveness can be improved. In this specification, the main bending direction is an arbitrary displacement direction that causes the plate-like structure to be bent in the thickness direction. The thickness direction is the direction in which the length is the shortest with respect to the dimensions of the plate-like structure.

(2) In the vibration-type angular velocity sensor for achieving the above object, the spring constant stabilizing means includes a main bending direction coinciding with an extending direction of the beam portion and a coupling with the beam portion in the main bending direction. It may have the form of a leaf spring.
According to the present invention, the spring constant stabilizing means having the form of a leaf spring is bent in the extending direction of the beam portion, thereby suppressing the extension of the beam portion. Therefore, a vibration type angular velocity sensor with high sensitivity can be realized. In addition, by setting the spring constant in the main deflection direction of the spring constant stabilizing means having the form of a leaf spring to a sufficiently large value, it is possible to prevent the natural frequency of the weight portion from being significantly lowered.

(3) In the vibration-type angular velocity sensor for achieving the above object, the support portion, the weight portion, and the beam portion are formed of a laminated structure, and the support portion or the weight portion in the lamination direction of the laminated structure. The spring constant stabilizing means may be formed by a hole penetrating through the damper, and the damper may be made of a resin material filled in the hole.
According to the present invention, since the laminated structure of the spring constant stabilizing means and the rest of the support portion or the weight portion is the same, the spring constant stabilizing means can be formed in a simple manufacturing process. Further, since the damper is formed by filling the hole with a resin material, the damper can be formed in a simple manufacturing process.

FIG. 1A is a perspective view according to an embodiment of the present invention. 1B and 1C are side views according to an embodiment of the present invention. The graph concerning embodiment of this invention. The graph concerning embodiment of this invention. The perspective view concerning the embodiment of the present invention. FIG. 5A is a top view according to the embodiment of the present invention. 5B is a cross-sectional view taken along line BB shown in FIG. 5A. FIG. 5C is a cross-sectional view taken along line CC shown in FIG. 5A. FIG. 5D is a partial view of FIG. 5A. Sectional drawing concerning embodiment of this invention. Sectional drawing concerning embodiment of this invention. Sectional drawing concerning embodiment of this invention. Sectional drawing concerning embodiment of this invention. The top view concerning the embodiment of the present invention. The top view concerning the embodiment of the present invention. Sectional drawing concerning embodiment of this invention. Sectional drawing concerning embodiment of this invention.

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. In addition, the same code | symbol is attached | subjected to the corresponding component in each figure, and the overlapping description is abbreviate | omitted.
1. Hard Spring Effect and Its Suppression Principle As shown in FIG. 1A, when both ends of the beam R are fixed to the two supports S1 and S2, the relationship between the displacement a and the restoring force F in the thickness direction of the beam R will be considered. In the range where the displacement a of the intermediate point of the beam R is small, the Hooke's law F = ka is approximately established. The spring constant k is a function of the displacement a. When the displacement a increases, the spring constant k increases and the beam R becomes hard as a spring.

FIG. 2 is a graph showing the relationship between the amplitude and frequency of the intermediate point of the beam R for each magnitude (amplitude) of the drive voltage for exciting the beam R. As the drive voltage V increases, the amplitude of the beam R increases. Further, the amplitude of the beam R increases as the frequency of the drive voltage V approaches the natural frequency. When excitation is performed at a relatively high drive voltage V ₄ , the beam R has a maximum amplitude at a higher frequency than excitation at a relatively low drive voltage V ₁ . That is, as the amplitude of the intermediate point of the beam R increases, the natural frequency of the intermediate point of the beam R increases. This is because the spring constant k in the thickness direction, which is the main bending direction of the beam R, increases as the displacement a of the intermediate point of the beam R increases. This is called the hard spring effect.

When exciting the relatively low driving voltages V _1, the amplitude and frequency of the relationship between the midpoint of the beam to the boundary of the natural frequency where the amplitude of the midpoint of the beam R becomes maximal R is symmetric. On the other hand, when excitation is performed at a relatively high drive voltage V ₄ , as shown by a solid line in FIG. 3, the frequency is within a range where the vibration occurs at a frequency higher than the natural frequency at which the amplitude of the intermediate point of the beam R is maximized. The absolute value of the rate of change of the amplitude with respect to is larger than the range of vibration at a frequency lower than the natural frequency at which the amplitude is maximized. If the absolute value of the change rate of the amplitude with respect to the frequency becomes large, it becomes difficult to control the amplitude by the drive voltage. That is, it is difficult to stably excite the beam R with a large amplitude. In the graph shown in FIG. 3, the solid line indicates the relationship between the amplitude and the frequency of the intermediate point of the beam R when the beam R is excited at the drive voltage V ₄ , and the broken line is the frequency at which the amplitude is maximized. The relationship between the vibration frequency and the amplitude of the intermediate point of the beam R is symmetric.

  By the way, as shown in FIG. 1B, when the positions of the supports S1 and S2 are relatively fixed, the beam R extends as the displacement a increases. Therefore, the hard spring effect is suppressed by reducing the elongation per unit length of the beam R accompanying the displacement a.

  As shown in FIG. 1C, when the beam R is supported so that the distance d between the supports S1 and S2 to which both ends of the beam R are fixed decreases as the displacement a increases, the unit of the beam R associated with the displacement a The elongation per length can be reduced. That is, when the distance d between the supports S1 and S2 is reduced according to the tension of the beam R, the elongation per unit length of the beam R accompanying the displacement a can be reduced. Therefore, the hard spring effect can be suppressed by causing at least one of the support S1 and the support S2 to function as a spring in the extending direction of the beam R.

  However, if at least one of the support S1 and the support S2 is made to function as a spring in the extending direction of the beam R, the intermediate point of the beam R is more specific than when the positions of the supports S1 and S2 are relatively fixed. The frequency will be low. Therefore, in order to maintain the natural frequency of the intermediate point of the beam R, it is preferable that the spring constants of the support S1 and the support S2 in the length direction of the beam R are larger. Further, in order to reduce the elongation per unit length of the beam R due to the displacement a, the spring constants of the support S1 and the support S2 in the length direction of the beam R are set such that the spring constant of the beam R in the extending direction of the beam R is It is preferably smaller than the spring constant.

  If the supports S1 and S2 are configured to vibrate as springs in the same direction as the vibration direction of the intermediate point of the beam R, the natural frequency of the intermediate point of the beam R varies greatly. Therefore, the supports S1 and S2 are configured to function as springs in the extending direction of the beam R and to function as substantial rigid bodies in the vibration direction of the intermediate point of the beam R. That is, the supports S1 and S2 are in the form of leaf springs in which the main bending direction coincides with the extending direction of the beam R and is coupled to the beam R in the main bending direction. The leaf spring has a small spring constant in the main deflection direction having a component in the thickness direction, and is so large that the spring constant can be treated as substantially infinite in the direction parallel to the plane perpendicular to the thickness direction. Accordingly, the supports S1 and S2 may be in the form of a leaf spring in which the thickness direction coincides with the extending direction of the beam R and is coupled to the beam R in the thickness direction.

2. First Embodiment FIGS. 4 and 5 show a first embodiment of a vibration type angular velocity sensor according to the present invention. For convenience of description, orthogonal xyz axes are defined as shown in FIGS. The vibration type angular velocity sensor 1 is configured as a MEMS and is a laminated structure of single crystal silicon, silicon oxide, platinum, PZT (lead zirconate titanate), etc., and is accommodated in a package (not shown). The vibration type angular velocity sensor 1 includes a frame-shaped support portion 10, a weight portion 15 having a cross-shaped bottom body, beam portions 12a, 12b, 12c, and 12d.

  Since the support part 10 is fixed to the package and is sufficiently thicker than the beam part 12, it behaves substantially as a rigid body. The support part 10 may have any form as long as it forms a space in which the beam part 12 and the weight part 15 are accommodated and behaves substantially as a rigid body.

  Each of the four beam portions 12 has one end coupled to the support portion 10 and the other end coupled to the weight portion 15. Specifically, the two layers 104 and 106 constituting the beam portion 12 also constitute the support portion 10 and the weight portion 15, and the layers 104 and 106 are continuous over the weight portion 15, the beam portion 12 and the support portion 10. As a result, the beam portion 12 is coupled to the support portion 10 and the weight portion 15. Since the four beam portions 12 do not include the thick layer 100 that protrudes from the plurality of layers constituting the weight portion 15 and the support portion 10, the four beam portions 12 are sufficiently thin in the z direction with respect to the weight portion 15 and the support portion 10. . Therefore, each of the four beam portions 12 behaves as an elastic beam having one end fixed to the support portion 10. The four beam portions 12 are aligned in parallel to the xy plane, and all extend in a direction parallel to the x-axis. The pair of beam portions 12a and 12b are aligned in the x direction, and extend from the one end portion of the weight portion 15 in the y direction to the support portion 10 in the opposite directions (x axis positive direction and x axis negative direction). The pair of beam portions 12c and 12d are aligned in the x direction, and extend from the other end portion of the weight portion 15 in the y direction to the support portion 10 in opposite directions (x axis positive direction and x axis negative direction). One main surface of the beam portion 12, the support portion 10, and the weight portion 15 is aligned in parallel with the xy plane. That is, the relatively thin beam portion 12 in the z direction is coupled to the z-direction ends of the support portion 10 and the weight portion 15 that are relatively thick in the z direction.

  The weight portion 15 is supported by the four beam portions 12 so as to be movable with respect to the support portion 10. The weight portion 15 behaves as a rigid body that moves three-dimensionally in an xyz coordinate system fixed to the support portion 10. Since the beam portion 12 that is relatively thin in the z direction is coupled to the end portion in the z direction of the weight portion 15 that is relatively thick in the z direction, the center of gravity of the weight portion 15 is from the plane including the beam portion 12. Separated in the z direction. Therefore, when an inertial force in the x direction or the y direction acts on the weight portion 15, the motion of the center of gravity of the weight portion 15 becomes a motion accompanied by rotation around the x axis or the y axis.

  A driving piezoelectric element 13 is provided as an excitation means in the vicinity of the boundary between the surface of each beam portion 12 and the support portion 10. The weight 15 is vibrated by applying an alternating drive voltage to the drive piezoelectric element 13. In the present embodiment, the reference vibration in the x-axis direction and the reference vibration in the y-axis direction are generated at different times by time-division driving. In order to simultaneously generate the reference vibration in the x-axis direction and the reference vibration in the y-axis direction, for example, a drive signal applied to the driving piezoelectric element 13a and the driving piezoelectric element 13d, the driving piezoelectric element 13b, and the driving piezoelectric element. What is necessary is just to shift the phase with the drive signal applied to 13c.

  The beam portion 12 and the weight portion 15 are configured such that the natural frequency of the center of gravity of the weight portion 15 is different in the x-axis direction, the y-axis direction, and the z-axis direction. This is to prevent so-called mechanical coupling in which the reference vibration in the x-axis direction leaks to the y-axis and the z-axis, or the reference vibration in the z-axis direction leaks to the x-axis and the y-axis. In this embodiment, the beam portion 12 and the weight portion 15 are configured so that the natural frequency increases in the order of the z-axis direction, the x-axis direction, and the y-axis direction (see Table 2 below).

  A detecting piezoelectric element 14 is provided as a detecting means in the vicinity of the boundary with the weight portion 15 on the surface of each beam portion 12. The detection piezoelectric element 14 detects the movement of the weight portion 15 relative to the support portion 10.

  When the vibration type angular velocity sensor 1 rotates around the x axis, a Coriolis force parallel to the y axis acts on the center of gravity of the weight portion 15 traveling in the z axis direction. When the weight portion 15 vibrates in the z-axis direction, the Coriolis force parallel to the y-axis accompanying the rotation around the x-axis also vibrates. Therefore, when the vibration type angular velocity sensor 1 rotates around the x-axis, the center of gravity of the weight portion 15 becomes It vibrates parallel to the y axis at the same frequency as the reference vibration of the z axis. When the center of gravity of the weight portion 15 is displaced parallel to the y-axis, the pair of detection piezoelectric elements 14a and 14b and the pair of detection piezoelectric elements 14c and 14d expand and contract as the weight portion 15 rotates about the x-axis. Vice versa. That is, when the pair of detection piezoelectric elements 14a and 14b extends, the pair of detection piezoelectric elements 14c and 14d contracts, and when the pair of detection piezoelectric elements 14a and 14b contracts, the pair of detection piezoelectric elements 14c and 14d extends.

  When the vibration-type angular velocity sensor 1 rotates around the y-axis, a Coriolis force parallel to the z-axis acts on the center of gravity of the weight portion 15 traveling in the x-axis direction. When the weight portion 15 vibrates in the x-axis direction, the Coriolis force parallel to the z-axis accompanying the rotation around the y-axis also vibrates. Therefore, when the vibration type angular velocity sensor 1 rotates around the y-axis, the center of gravity of the weight portion 15 becomes It vibrates parallel to the z axis at the same frequency as the reference vibration of the x axis. When the center of gravity of the weight portion 15 is displaced parallel to the z-axis, the four detection piezoelectric elements 14a, 14b, 14c, and 14d are aligned in the expansion / contraction direction. That is, the four detection piezoelectric elements 14a, 14b, 14c, and 14d simultaneously extend and contract simultaneously.

  When the vibration type angular velocity sensor 1 rotates around the z-axis, a Coriolis force parallel to the y-axis acts on the center of gravity of the weight portion 15 that advances in the x-axis direction. When the weight portion 15 vibrates in the x-axis direction, the Coriolis force parallel to the y-axis accompanying the rotation around the z-axis also vibrates. Therefore, when the vibration type angular velocity sensor 1 rotates around the z-axis, the center of gravity of the weight portion 15 becomes It vibrates parallel to the y-axis at the same frequency as the reference vibration of the x-axis.

  A circuit for detecting an angular velocity around each axis of xyz based on the output signals of the four detection piezoelectric elements 14 and the drive signal applied to the drive piezoelectric element 13 and the drive signal applied to the drive piezoelectric element 13 are output. The time-division driving circuit may be formed on a die constituting the vibration type angular velocity sensor 1 or may be formed on a die different from the die constituting the vibration type angular velocity sensor 1.

  As described above, in order to suppress the hard spring effect while maintaining the natural frequencies of the four beam portions 12, a spring portion 11 is formed on the support portion 10 for each beam portion 12 as a spring constant stabilizing means. The spring portion 11 is an L-shaped plate-like portion located between the hole 10h formed in the vicinity of the inner peripheral surface of the support portion 10 and the inner peripheral surface of the support portion 10, and is equally spaced in FIG. This is the part indicated by hatching. A hole 10 h that separates the spring portion 11 and the remaining portion of the support portion 10 passes through the support portion 10. The spring portion 11 separated from the remaining portion of the support portion 10 by a hole 10 h penetrating the support portion 10 has the same laminated structure as the remaining portion of the support portion 10. Accordingly, the length W of the spring portion 11 in the z direction is constant and equal to the length of the remaining portion of the support portion 10 in the z direction. One of the spring portions 11 extends in parallel with the y-axis with the bent portion as a boundary, and the other extends in parallel with the x-axis, and both ends are coupled to the remaining portion of the support portion 10.

One end of the beam portion 12 is coupled to one end in the z direction at a portion extending in parallel with the y-axis of the spring portion 11. Specifically, the two layers 104 and 106 constituting the beam portion 12 also constitute the spring portion 11, and the layers 104 and 106 are continuous over the spring portion 11 and the beam portion 12. The spring portion 11 is coupled. The main deflection direction of the spring portion 11 in the joint portion with the beam portion 12 is the thickness direction (x direction) of the spring portion 11, and the extending direction of the beam portion 12 (the end coupled to the weight portion 15 and the support portion 10). (The direction connecting the joining ends). Along with the tension of the beam portion 12, the joint portion of the spring portion 11 with the beam portion 12 is displaced in the x-axis direction. The relationship between the displacement in the x-axis direction of the joint portion of the spring portion 11 with the beam portion 12 and the restoring force in the x-axis direction of the spring portion 11 accompanying this displacement, that is, the x-axis direction of the spring portion 11 (the extension of the beam portion 12 (Direction) spring constant correlates with the dimensions T ₁ , T ₂ , L ₁ , L ₂ , L ₃ and W of each part shown in FIGS. 5B and 5D. The relationship between the spring constant of the spring part 11 in the x-axis direction and L ₁ , L ₂ , L ₃ is a negative correlation. The relationship between the spring constant of the spring portion 11 in the x-axis direction and T ₁ , T ₂ , W is a positive correlation. That is, in order to increase the spring constant of the spring portion 11 in the x-axis direction, T ₁ and T ₂ corresponding to the thickness of the leaf spring and W corresponding to the width of the leaf spring are increased to correspond to the length of the leaf spring. L ₁ , L ₂ , and L ₃ to be performed may be reduced. The form of the spring portion 11 is set by the position and size of the hole 10 h formed in the support portion 10. Since the hole 10 h penetrates the support part 10, the spring part 11 is fixed to the remaining part of the support part 10 on both sides. The hole 10 h may be configured so as not to penetrate the support portion 10, and in this case, the spring portion 11 has a configuration in which three sides are fixed to the remaining portion of the support portion 10. The thicknesses T ₁ and T ₂ of the spring part 11 may be changed with the bent part as a boundary. When the x-axis and extending in parallel portions of the spring portion 11 sufficiently thick (the T ₂ greater) and sufficiently short (reduced L ₃₎ design, only a portion extending parallel to the y-axis of the spring portion 11 as a substantially spring Function. Since the length (width) W in the z direction of the spring portion 11 is sufficiently larger than the thicknesses T ₁ and T ₂ , the spring constant in the z direction of the spring portion 11 is considered to be substantially infinite. That is, the spring portion 11 is elastically deformed in the x direction, which is the extending direction of the beam portion 12, but is not deformed in the z direction, which is the main bending direction of the beam portion 12. When the coupling portion between the spring portion 11 and the beam portion 12 is fixed in the z direction, which is the main deflection direction of the beam portion 12, the natural frequency of the weight portion 15 is compared to when the coupling portion is displaced in the z direction. Can be high.

  As shown in FIG. 5B, when the end portions in the z direction of the support portion 10, the beam portion 12, and the weight portion 15 are aligned parallel to the xy plane, and the beam portion 12 is not bent at all, the weight portion 15 When the frame moves with respect to the support portion 10, the tension of at least one of the four beam portions 12a, 12b, 12c, and 12d increases. Since the spring part 11 bends according to this increase in tension, the extension of the beam part 12 and the increase in the spring constant accompanying the increase in tension are suppressed. Specifically, for example, when the center of gravity of the weight portion 15 is displaced in the z direction from the initial state, the tensions of the four beam portions 12a, 12b, 12c, and 12d all increase, and the beam portions 12a, 12b, 12c, and 12d respectively The coupled spring portions 11a, 11b, 11c, and 11d bend in the x-axis direction as the tension of the beam portions 12a, 12b, 12c, and 12d increases. That is, the increase in the spring constant in the z direction of the beam portion 12a accompanying the extension of the beam portion 12a is caused by the spring portion 11a, and the increase in the spring constant in the z direction of the beam portion 12b accompanying the extension of the beam portion 12b is caused by the spring portion 11b. An increase in the spring constant in the z direction of the beam portion 12c due to the extension of the beam portion 12c is suppressed by the spring portion 11c, and an increase in the spring constant in the z direction of the beam portion 12d due to the extension of the beam portion 12d is suppressed by the spring portion 11d, respectively. Is done.

  On the other hand, the spring constant of the beam portion 12 in the x direction, which is the extending direction of the beam portion 12, is sufficiently larger than the spring constant of the beam portion 12 in the z direction, which is the main deflection direction of the beam portion 12. Therefore, even if the spring constant in the x direction of the spring portion 11 is set to be sufficiently larger than the spring constant in the z direction of the beam portion 12, the extension of the beam portion 12 is suppressed and the spring constant in the z direction of the beam portion 12 is reduced. The increase can be suppressed. Then, by setting the spring constant in the x direction of the spring portion 11 to be sufficiently larger than the spring constant in the z direction of the beam portion 12, changes in the natural frequency of the center of gravity of the weight portion 15 can be suppressed.

  In order to realize the reference vibration in the x-axis direction and the z-axis direction individually by time-division driving, it is necessary to quickly attenuate the vibration in order to switch the direction of the reference vibration. Therefore, the inside of the hole 10 h is filled with the damper 20 and the damper 20 is coupled to the support portion 10. In FIG. 5, the damper 20 is indicated by resin hatching. As a material of the damper 20, a resin such as polyimide having a smaller elastic modulus and Q value than the beam portion 12 than the spring portion 11 is used. By providing such a damper 20 in the spring portion 12, the Q value can be lowered.

3. Manufacturing Method FIGS. 6 to 9 are cross-sectional views showing a manufacturing method of the vibration type angular velocity sensor 1 shown in FIG. 8A and 9A show a cross section taken along line BB shown in FIG. 5, and FIGS. 8B and 9B show a cross section taken along line CC shown in FIG.

  First, as shown in FIG. 6, an SOI (Silicon On Insulator) substrate composed of a single crystal silicon layer 100 having a thickness of 625 μm, a silicon oxide layer 102 having a thickness of 1 μm, and a single crystal silicon layer 104 having a thickness of 10 μm is thermally oxidized. Thus, an insulating layer 106 having a thickness of 0.5 μm is formed. Subsequently, an electrode layer 108 made of platinum having a thickness of 0.1 μm, a piezoelectric layer 110 made of PZT having a thickness of 3 μm, and an electrode layer 112 made of platinum having a thickness of 0.1 μm are sequentially stacked on the insulating layer 106 by sputtering. To do.

  Next, as shown in FIG. 7, the electrode layers 108 and 112 and the piezoelectric layer 110 are patterned into a predetermined shape by a milling method using two types of protective film portions (not shown) made of photoresist. As a result, the driving piezoelectric element 13 and the detection piezoelectric element 14 including the electrode layers 108 and 112 and the piezoelectric layer 110 and the wiring elements (conductive wires and bonding pads) (not illustrated) including the electrode layers 108 and 112 are formed.

  Next, as shown in FIG. 8, the insulating layer 106 and the single crystal silicon layer 104 are patterned into a predetermined shape by reactive ion etching using a protective film portion (not shown) made of a photoresist. As a result, a pattern of the beam portion 12 composed of the insulating layer 106 and the single crystal silicon layer 104 is formed, and an upper layer portion of the spring portion 11 and the weight portion 15 is formed. Moreover, the upper layer part of the hole 10h for forming the spring part 11 in the support part 10 is formed.

  Next, as shown in FIG. 9, the single crystal silicon layer 100 is patterned into a predetermined shape by Deep-RIE (Reactive Ion Etching) using a protective film portion (not shown) made of a photoresist. As a result, the lower layer part of the spring part 11 and the weight part 15 is formed. In addition, a lower layer portion of the hole 10 h for forming the spring portion 11 is formed in the support portion 10.

  Next, the exposed portion of the silicon oxide layer 102 is removed by etching. As a result, the hole 10h of the support part 10 penetrates, and the beam part 12, the spring part 11, and the weight part 15 are released.

  Next, the damper 20 is coupled to the spring portion 11. Specifically, for example, the resin material may be filled after filling the hole 10h using a dispenser or the like, and after the photosensitive resin is applied and filled into the hole 10h, unnecessary portions are removed by a photolithography technique. It may be left in the hole 10h.

  Thereafter, when a post-process such as dicing is performed, the vibration type angular velocity sensor 1 shown in FIGS. 4 and 5 is completed.

  When the spring portion 11 has the same layer structure as the remaining portion of the support portion 10 because the hole 10h of the support portion 10 penetrates the support portion 10, the case where the support portion 10 without the spring portion 11 is manufactured and the protective film The spring part 11 can be formed by the above-described manufacturing method, which is the same except that the pattern of the part is different. That is, when the spring part 11 is formed by the hole 10h penetrating the support part 10, the spring part 11 can be formed without adding a process.

8). Other Embodiments The technical scope of the present invention is not limited to the above-described embodiments, and it goes without saying that various modifications can be made without departing from the scope of the present invention.
For example, as shown in FIG. 10, four beam portions 12a, 12b, 12c, and 12d are coupled to two spring portions 11a and 11b, and a damper 20 is provided in a hole 10h that forms the spring portions 11a and 11b. Also good. Further, for example, as shown in FIG. 11, spring portions 16a, 16b, 16c and 16d are formed in the weight portion 15, and the damper 20 is provided in the hole 15h forming the spring portions 16a, 16b, 16c and 16d. good.

  Further, instead of completely filling the hole 10 h of the support portion 10 with the damper 20, a part of the hole 10 h may be filled with the damper 20 as shown in FIGS. 12 and 13. Since the beam portions 12a and 12b are coupled to the ends in the width direction (z direction) of the spring portions 11a and 11b constituting the wall surface of the hole 10h, when the beam portions 12a and 12b are bent in the z direction, the spring portions 11a and 11b are twisted. At this time, the increase / decrease in the cross-sectional area obtained by cutting the hole 10h in parallel with the xy plane is reversed between the end portion closer to the beam portions 12a and 12b and the end portion farther away. Accordingly, when the hole 10h of the support portion 10 is completely filled with the damper 20, the volume change of the damper 20 is partially offset internally. On the other hand, as shown in FIG. 12 and FIG. 13, when the damper 10 is filled up to about half from one end of the hole 10 h, the volume change of the damper 20 is not offset internally, so the vibration damping effect by the damper 20 is reduced. Can be increased.

  Moreover, as shown in FIG. 13, both ends of the hole 10h may be closed with damper materials 20a and 20b, and air may be sealed inside the hole 10h. In this case, the damper materials 20a and 20b themselves function not only as a damper, but also the air sealed inside the hole 10h functions as a damper. When air sealed mainly inside the hole 10h is caused to function as a damper, both ends of the hole 10h may be closed with a resin film such as a photosensitive dry film. As shown in FIG. 13, the following method may be used to fill the inside of the hole 10h with the damper material 20b and to close one end of the hole 10h with the damper material 20a. That is, first, after filling the hole 10h with a photosensitive resin such as a photoresist, unnecessary portions are removed by a photolithography technique in which the exposure depth is controlled to form the damper material 20b. Next, a photosensitive dry film is attached to close one end of the hole 10h, and unnecessary portions of the photosensitive dry film are removed by exposure / development to form the damper material 20a.

  Further, the spring constant stabilizing means is not limited to the form of a leaf spring. For example, in the vicinity of the boundary with the beam portion, a region in which the rigidity is reduced in the extending direction of the beam portion by a hole penetrating the support portion or the weight portion in the stacking direction is used as a spring. It may be configured as a constant stabilizing means, or a honeycomb structure formed by a plurality of holes penetrating the support portion or the weight portion in the stacking direction may be configured as the spring constant stabilizing means. Further, the excitation means for exciting the weight portion may be realized using electrostatic attraction or electromagnetic force. Further, the detection means for detecting the movement of the weight portion may be realized using a capacitance or a piezoresistance effect. The materials, dimensions, and manufacturing methods shown in the above embodiment are merely examples, and descriptions of modifications that are obvious to those skilled in the art are omitted.

1: vibration type angular velocity sensor, 2: vibration type angular velocity sensor, 3: vibration type angular velocity sensor, 10: support part, 10h: hole, 11a: spring part, 11b: spring part, 11c: spring part, 11d: spring part, 12a: beam part, 12b: beam part, 12c: beam part, 12d: beam part, 13a: driving piezoelectric element, 13b: driving piezoelectric element, 13c: driving piezoelectric element, 13d: driving piezoelectric element, 14a: Piezoelectric element for detection, 14b: Piezoelectric element for detection, 14c: Piezoelectric element for detection, 14d: Piezoelectric element for detection, 15: Weight part, 16b: Spring part, 16c: Spring part, 16d: Spring part, 16e: Spring part , 100: single crystal silicon layer, 102: silicon oxide layer, 104: single crystal silicon layer, 106: insulating layer, 108: electrode layer, 110: piezoelectric layer, 112: electrode layer, R: beam, S1: support, S2: Support

Claims (3)

A support part;
A weight part;
A plurality of beam portions extending from the weight portion to the support portion and supporting the weight portion;
Excitation means for exciting the weight part in a plurality of directions by time-division driving;
Detecting means for detecting movement of the weight portion with respect to the support portion;
It is formed in the vicinity of the boundary between at least one of the support part and the weight part with the beam part, elastically deforms in the extending direction of the beam part according to the tension of the beam part, and substantially in the main bending direction of the beam part. Spring constant stabilizing means that does not deform
A damper that is coupled to the spring constant stabilizing means to damp vibrations of the spring constant stabilizing means;
A vibration type angular velocity sensor comprising: The spring constant stabilizing means has a form of a leaf spring in which the main bending direction coincides with the extending direction of the beam portion and is coupled to the beam portion in the main bending direction.
The vibration type angular velocity sensor according to claim 1. The support portion, the weight portion, and the beam portion are made of a laminated structure,
The spring constant stabilizing means is formed by a hole penetrating the support portion or the weight portion in the stacking direction of the stacked structure,
The damper is made of a resin material filled in the hole.
The vibration type angular velocity sensor according to claim 1 or 2.

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